Potato clock

Untimely scientific discovery?

We've all seen them on the Mr. Wizard television show or seen them in some science/nature stores, but what are they and how do they work? First of all, I'm talking about the elusive Potato Clock. Yes folks, a real clock that tells actual time by running off of two potatoes. Right now I'm sure you're asking yourself how they work or how you could make one yourself... so here you go. Listed is everything one needs to know about how to make this modern marvel and how it operates (for all you cheap bastards, science buffs out there):

What you'll need:

1. Two potatoes*
2. Eight inch jumper wire (any electrical wire will do really...)
3. Two strips of pure Copper
4. Two strips of pure Zinc
5. An LCD display clock you can fasten the wires to
6. A base or stand (if desired)

What to do:

Place the LCD clock display between the two potatoes*. Cut two moderately lengthy pieces of your jumper wire and on one fasten a strip of Zinc and on the other fasten a strip of Copper. Connect the two wires to different terminals on the LCD display and then insert the strips of elements into the opposing potatoes. Your current situation should look something like this...

      ____________                    ____________      
     |            |                  |            |     
     |            |                  |            |     
    _#_           |                  |           _@_    
  _/   \_         |                  |         _/   \_  
 /       \        |                  |        /       \ 
|         |       |__________________|       |         |
|         |       | ________________ |       |         |
|         |       ||                ||       |         |
| Potato1 |       ||                ||       | Potato2 |
|         |       ||________________||       |         |
|         |       |__________________|       |         |
|         |                                  |         |
 \_     _/                                    \_     _/ 
   \___/                                        \___/   

By the way, the pound sign denotes Copper while the ampersand denotes Zinc. Next, use the remaining length of your wire and on one end fasten the other piece of copper while on the other end fasten the other piece of zinc. Then, take the wire you just made and jam it into both potatoes, making sure you have both types of metals in both potatoes. After that step's done... Poof! You have a potato clock that should be running by now. Use the instructions that came with your LCD clock display to set the time. Your finished product should look a little something like this:

      ____________                    ____________      
     |            |                  |            |     
     |            |                  |            |     
    _#_           |                  |           _@_    
  _/   \_         |                  |         _/   \_  
 /       \        |                  |        /       \ 
|         |       |__________________|       |         |
|         |       | ________________ |       |         |
|         |       ||                ||       |         |
| Potato1 |       ||    12 : 32     ||       | Potato2 |
|         |       ||________________||       |         |
|         |       |__________________|       |         |
|         |                                  |         |
 \_     _/                                    \_     _/ 
   \___/@--------------------------------------#\___/   

By now you're probably wondering what the little *'s mean by the word potato. Well these denote that the actual thing that you use to plug the wires into could be replaced with...

Eventually the potato or whatever you're using will have to be replaced, but you know that because you have intuition! So there you have it. You're now the proud owner of the official Two Potato Clock. But since you're inquisitive, you're still asking yourself, "Well, I'm really excited that I have one... but how does it work?" I'm glad you asked that.

In the whole realm of the potato clock (a big Oxidation/Reduction Reaction of sorts), the potatoes just serve as electrolytes that transfer electrons through the wire to the clock and back to the other potato, creating a circuit. Zinc is labeled as the Anode and Copper is known as the Cathode. Because Zinc is reacting with the existing Zinc in the potatoes, it creates excess electrons, thusly causing it to slowly desintegrate. These electrons flow through the wires and are intercepted by the opposite ends containing Copper. So because Zinc is losing its electrons, it's the Oxidation part of the circuit. To explain what's happening to Zinc, here's the chemical equation of what occurs to this element when it's jammed in the potato:

Zn ---> Zn⁺² + 2^e-

Because Copper is the recipient of Zinc's excess electrons, it's known as the Reduction part of the circuit. Here's Copper's chemical equation:

Cu⁺² + 2^e- ---> Cu

As this equation states, Copper obtains the loose electrons and creates more copper from them. So as the Zinc depletes, the Copper is continuously coating itself with layers of newly formed Copper.

The battery/circuit created by this mechanism yields roughly a half of a volt, but that's just enough to power a small LCD clock. A good thing to keep in mind is to keep the element ends of the wires close, but separated. If they're touching, the reaction will still occur but only heat will be produced. Although heat could be converted to energy, it would completely eradicate the essence of the original potato clock so it's not recommended.

Well I hope this explained some about the funny little thing known as the potato clock! So have fun and enjoy... say, what time is it?